1. Field of the Invention
The present invention relates to a neural stimulating lead including a stabilizing mechanism. More specifically, tne present invention relates to a stimulating lead incuding a stabilizing mechanism which is adapted for movement within an epidural space of a vertebrum to stabilize the positioning of an electrode of the lead at a desired location along the spinal cord traversing the vertebrae of the spine.
2. Description of the Prior Art
Heretofore, stimulating leads for use in spinal cord stimulation have had a tendency to migrate after placement. The migration has a considerable effect on stimulation no matter how miniscule the migration is. In this respect, migration of a stimulating lead will lead to poor electrical contact of the electrode with the spinal cord or will lead to stimulation of an improper area of the spinal cord which will negate the effect required, such as stimulation of a precise area to alleviate pain.
To overcome such migration, various solutions have been proposed, such as, for example, button electrodes for S-shaped leads. Examples of some of these proposed solutions are disclosed in the following U.S. Patents:
The Ackerman U.S. Pat. No. 3,516,412 discloses a bipolar electrode which is fed through a needle to a desired point of lodgement and, when the needle is withdrawn, the electrode end bends to an angle of up to 90.degree. C. to provide secure placement of a tip of the electrode against tissue.
The Hess U.S. Pat. No. 4,285,347 discloses a neural electrode lead with stabilizing structure. The stabilizing structure here is in the form of lateral expandable loop elements.
The Dickhudt et al. U.S. Pat. No. 4,414,986 discloses a biomedical stimulation lead which has perpendicularly extending tines located at a tip of a lead body. Further, the lead body, proximal to the electrode, is provided with a helical configuration to add another stabilizing element which stabilizes the electrode during the period immediately after implantation.
The Dickhudt et al. U.S. Pat. No. 4,419,819 discloses a biomedical lead with lobed lead anchor. The anchor comprises a sleeve which is slit in a direction parallel to the axis of the lead body and when the tubing is compressed, the slit portions expand into lobes to stabilize the position of a lead electrode therein.
As will be described in greater detail hereinafter, the lead of the present invention includes a stabilizing mechanism which comprises a tine that is movable from a retracted position to an extended position for securing an electrode against spinal cord tissue. Further, the tine is retractable when it is desired to remove the lead.